Rotor Inertia

Correct Answer

B — Their inherent inertia limits fast speed changes.

Explanation

Rapid speed change requires large accelerating/decelerating torque relative to the combined mechanical inertia. The rotor and connected mechanical system therefore limit how quickly speed can change, making option B the best answer among the choices.

Key Concept

Rotor Inertia

Exam Point

Dynamic speed response is fundamentally limited by torque-to-inertia ratio.